He told James Madison: "I think our governments will remain virtuous for many centuries as long as they are chiefly agricultural; and this will be as long as there shall be vacant lands in any part of America. When they get plied upon one another in large cities, as in Europe, they will become corrupt as in Europe."

What are proper densities for city dwellings? … Proper city dwelling densities are a matter of performance … Densities are too low, or too high, when they frustrate city diversity instead of abetting it …

Very low densities, six dwellings or fewer to the net acre, can make out well in suburbs … Between ten and twenty dwellings to the acre yields a kind of semisuburb …

However densities of this kind ringing a city are a bad long-term bet, designed to become a grey area. …

And so, between the point where semisuburban character and function are lost, and the point at which lively diversity and public life can arise, lies a range of big-city densities that I shall call “in-between” densities. They are fit neither for suburban life nor for city life. They are fit, generally, for nothing but trouble …

I should judge that numerically the escape from “in-between” densities probably lies somewhere around the figure of 100 dwellings to an acre, under circumstances most congenial in all other respects to producing diversity.

As a general rule, I think 100 dwellings per acre will be found to be too low.

Jacobs turns American Exceptionalism on its head. The urbanist reverence for density is a geographic fetish, as was Jefferson's utopian ideal. Such policy thinking is density for density's sake. Tony Hsieh's magic number for innovation:

Tony Hsieh talks about his Internet juggernaut Zappos in the same way that urban planners talk about cities. In fact, the language is uncanny. He believes the best ideas – and the best form of productivity – come from "collisions," from employees caroming ideas off one another in the serendipity of constant casual contact.

This is only achievable through density, with desks pushed close together in the office, or – in the case of Hsieh’s ambitious plans to leverage the new Zappos headquarters to remake downtown Las Vegas – with company employees and community members colliding into each other on the street. For the kind of "collisionable" density he’s looking for in downtown Vegas around his company, he figures the neglected area (not to be confused with the Vegas Strip) needs at least 100 residents per acre. ...

... His evolution in thinking, he says, comes more from his earlier days as a party planner. Close one bar in the corner of a room for example, he says, and you eliminate congestion points and enable people to better flow through a party. The challenge is all about creating circulation and serendipity.

Emphasis added. Fittingly, Hsieh's density evangelism comes from a misunderstanding. How many people you pack into a room isn't important. It's all about circulation. A party with less density and better circulation is better for knowledge exchange. Isolation (i.e. corner office), not lack of density, is the problem. The redevelopment of downtown Las Vegas is based on a poorly understood metaphor.

Of the 70-odd countries I've reported from, North Korea is perhaps the most illuminating. The world's last Stalinist dictatorship is hermetically sealed from the outside world. Hardly anyone is allowed out, and hardly anyone is allowed in (it wasn't easy getting a visa.)

Because North Korea shuts out people, it shuts out ideas. That's one big reason why it is a starving backwater. Its more open cousin, South Korea, which welcomes foreigners and sends hordes of students and businesspeople abroad each year, is 17 times richer.

South Koreans worry whether their children will make it to the right university; North Koreans worry whether their children will make it to the age of five.

The central message of my book, Borderless Economics, is that when people move around, they spread new ideas, mostly for the better.

For example, the world's cheapest fridge was born of a marriage of minds between Indians in America and Indians in India. Three Indian-American engineers (Uttam Ghoshal, Himanshu Pokharna and Ayan Guha) were working on a cooling device, based on technology used to cool laptops, that they thought might work in a fridge. One of them had trained at IBM, so he knew a thing or two about computers.

While back in India visiting relatives, they decided to show their design to an Indian manufacturer called Godrej and Boyce. It so happened that Godrej was already working on a super-cheap fridge for poor rural Indians. The two teams joined forces and produced a little fridge called the Chotu Kool that will sell for a mere $70 - less than half the price of rival fridges.

The circulation of people will beat density every time. There is nothing inherently magical about cities and density. Through people, a collision of two places can happen. Such serendipity is much more likely in South Korea than North Korea, density be damned.

8 comments:

Jim, I think you are on the right tack but I also think you discount the importance of density. I believe in the value of what I've called "flow" for cities (you've called it 'churn"). Many density proponents have mistaken density for flow/churn. It's becoming clearer that the two are exclusive -- density doesn't always mean churn is happening, and churn doesn't always create greater density. But Tony Hsieh and others recognize that at least creating a denser environment creates better chances for churn. Would you agree to that much?

But Tony Hsieh and others recognize that at least creating a denser environment creates better chances for churn. Would you agree to that much?

I don't see how greater density would improve churn. Hsieh doesn't make that case. In theory, density should increase the number of unique "collisions". Thus, porch culture in a dense urban neighborhood would catalyze more interactions than porch culture in a less dense suburban neighborhood. But that only works if people hang out on their front stoops.

Greater density has greater potential collisions.

The main issue is isolation. If an urban neighborhood is isolated and relatively inert (i.e. little to no churn), greater density won't help.

I understand other factors are relevant when looking globally, but if you take reasonably common conditions in the United States, then the connection is pretty straightforward. Density is conducive to walking around more. Walking around more, in the United States, typically leads to more "collisions".

It is useful to point out what else is required to make this work out as hoped, and similarly what can go wrong, but I don't think it makes sense to deny this basic insight.

Density is conducive to walking around more. Walking around more, in the United States, typically leads to more "collisions".

Walking around more is "flow". I appreciate how greater flow can lead to more collisions. The density variable is confusing the issue. The assertion that greater density leads to more flow and thus more collisions is specious.

Ultimately, Hsieh is talking about knowledge transfer and how ideas don't fall far from the tree. Case and point is the sprawl of industry clusters in Silicon Valley and the agglomeration of venture capital.

I'm not sure how "flow" is being defined, but walking around is different from most other modes of human movement in that it is conducive to casual interaction. You can't initiate the proverbial porch discussion with someone driving by, or with someone whisking by your office in an elevator, or so on, because their conveyance cuts them off from you. From the travelers perspective, there is usually little penalty in briefly pausing your walking to have such an interaction (contrast this with, say, stopping your car to speak with someone, which is done sometimes but is often inconvenient and potentially hazardous).

Walking is also distinctive in that is an extremely low-cost mode of travel for short distances (in fact accounting for the inherent pleasures of walking and the health benefits, the cost is arguably negative in many circumstances). Therefore, the mere ability to walk to potentially desirable destinations does have the ability to lead to increased trips outside of one's home/workplace.

So I wouldn't completely disparage the importance of having a lot more potentially desirable destinations within walking distance, because walking really isn't just like other modes of transportation. Of course more goes into "walkability" than just distance, but it certainly is an important part of the equation.

A neighborhood can be walkable at a variety of densities. Some neighborhoods have a more robust porch culture. You see more people mingling. It's not a function of density. Furthermore, much of the serendipity and knowledge spillovers happen at work. The residential densities don't impact innovation. In fact, dense urban neighborhoods that are isolated tend to be poor.

Yes, but not really below a certain minimum, which many post-WWII U.S. neighborhoods fall below. Plus "walkability" is not a binary variable--more potential destinations within a short pleasant walk will mean more walking around, although as with most such things there will likely be a diminishing marginal increase in walking at some point.

"Some neighborhoods have a more robust porch culture. You see more people mingling. It's not a function of density."

Well, it is not ONLY a function of density. Again, though, a certain minimum density is a necessary condition, and I believe increased density will, in the United States, be positively correlated with increased neighborhood mingling for a fairly broad range.

Just think in terms of how many doors you can visit with your kids on Halloween. Of course in some neighborhoods you don't see much trick-or-treating at all, but again that just means density is not the ONLY factor, which is different from the proposition it is not a factor at all.

"Furthermore, much of the serendipity and knowledge spillovers happen at work. The residential densities don't impact innovation."

I think the point about walkability applies to work environments as well. Of course many professional environments are already "dense" and "walkable" on a very local scale, but you might have a lot less walkability overall in, say, a work environment scattered over a bunch of one-story buildings versus a single multi-story building.

By the way, I am sympathetic to the idea of trying to combat xenophobia and give migration its proper place in economic development. But you can get there without denying that other factors play a role.